Fix up Info.plist when building LLDB.framework with CMake

Summary:
We weren't using the Info.plist template in resources previously.
When using that template, some of the key's values weren't being populated
because some variables were not being defined. In one case, CMake didn't
like the substring expansion syntax of CFBundleIdentifier so I got rid of that.

Differential Revision: https://reviews.llvm.org/D47792

llvm-svn: 335014